Truncatones A–D, benzo[j]fluoranthenes from Annulohypoxylon species (Xylariaceae, Ascomycota)

Abstract

From stromata (fruiting bodies) of three xylariaceous fungi belonging to the genus Annulohypoxylon (A. leptascum, A. cf. truncatum and an unidentified Annulohypoxylon sp.), truncatone A (1), three unprecedented derivatives named truncatones B–D (2–4) besides the known 4,5,4′,5′-tetrahydroxy-1,1′-binaphthyl (BNT, 5), hypoxylonol C (6) and hypoxylonol F (7) were isolated. Planar structures of the new benzo[j]fluoranthene derivatives 2–4 were determined on the basis of NMR and HRESIMS data. While the relative configuration of 4 was demonstrated by ROESY NMR data and1H,1H coupling constants, absolute configurations of 1, 2, 4 were determined by CD spectroscopy. Compounds 1, 3 and 4 exhibited cytotoxicity against the mouse fibroblast cell line L929.